CN104218535B - A kind of active PFC overcurrent protection circuits - Google Patents
A kind of active PFC overcurrent protection circuits Download PDFInfo
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- CN104218535B CN104218535B CN201310214110.3A CN201310214110A CN104218535B CN 104218535 B CN104218535 B CN 104218535B CN 201310214110 A CN201310214110 A CN 201310214110A CN 104218535 B CN104218535 B CN 104218535B
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Abstract
The present invention provides a kind of active PFC overcurrent protection circuits, has not only detected the electric current flowed through on power device, but also the electric current of detection DC loop.Overcurrent on power device is instantaneous value, detects the electric current flowed through on power device, when detecting that overcurrent occurs in the electric current on power device, stops the pwm pulse of output driving power device on off state in time.The current feedback detected on power device to MCU is middle fracture, and the response speed of middle fracture quickly in time protects power device, in case power device is damaged because of overcurrent.By detecting the corresponding first voltage signal of total current on commutating circuit, first voltage signal is fed back to the A/D mouths of MCU, when there is overcurrent, stop pwm pulse of the output to power device grid, when there is not overcurrent, the pulse width of pwm pulse is adjusted come closed loop feedback according to the size of first voltage signal（Or duty ratio）The effect of power factor compensation is set to get a promotion.
Description
Technical field
The present invention relates to power factor correction technology field, more particularly to a kind of active PFC overcurrent protection circuits.
Background technology
With the offer of commercial production levels and living standards of the people, the non-linear electrical equipment largely used is in power grid
More and more harmonic waves are produced, the loss of power grid power supply is not only increased, influences the normal operation of electric network protection device, and
Reduce the power factor of electrical equipment.
Transducer air conditioning just belongs to non-linear electrical equipment, therefore, in order to inhibit harmonic wave generation and provide power because
Number, introduces PFC in transducer air conditioning（PFC, Power Factor Correction）Technology.
The basic ideas of PFC are exactly that input current waveform tends to sine wave and small with input voltage phase subtractive as possible.
Currently, PFC technologies can be divided into passive power factor correction（PPFC）And active power factor correction（APFC）.
PPFC mainly forms filter using inductance and capacitance etc., the filter adjust input current waveform and
Phase offset.The advantages of PPFC is that circuit is fairly simple, at low cost, electromagnetic interference is few, the operation is stable.
APFC is mainly to control the make-and-break time of power switch component to adjust input current waveform and its phase offset.
The advantages of APFC is to improve power factor and reduce the harmonic components of electric current.
At present the world advocate it is energy saving, therefore in convertible frequency air-conditioner also become energy saving research emphasis.In order to
Reach the requirement of national " 3C " forcible authentication, current harmonics inhibits to solve the problems, such as convertible frequency air-conditioner producer；Due to passing
The passive PFC of system inhibits harmonic fashion that can not solve the high-energy-efficiency variable-frequency air-conditioning products that country is advocated, so active PFC is increasingly
As the mainstream scheme in convertible frequency air-conditioner industry.
Since environment complexity used in convertible frequency air-conditioner is various, badness is more（As being struck by lightning, stopping in power supply wink, power supply it is anxious
Change, abnormity of power supply etc.）；Also have the characteristics that operation power is wide, frequency is high, the fluctuation of load is big simultaneously.Therefore, to active PFC's
Reliability design proposes very high requirement, and the protection of wherein overcurrent is even more the key points and difficulties of research.How one kind is provided
Safer reliable overcurrent protection circuit is those skilled in the art's technical issues that need to address.
Invention content
The technical problem to be solved in the present invention is to provide a kind of active PFC current foldback circuits, can exist in pfc circuit
It is safer when overcurrent reliably to be protected.
The present invention provides a kind of overcurrent protection circuit of active PFC, including：First current sampling module, the second electric current
Sampling module and MCU；
First current sampling module, for acquiring the first current signal in DC power supply circuit, by described first
Current signal carries out being converted to the A/D mouths that corresponding first voltage signal is sent to the MCU；
Second current sampling module, for acquiring the second electric current flowed through on power device in active PFC circuit letter
Number, when second current signal is more than the second threshold current of setting, send middle fracture of the interrupt signal to the MCU；
The MCU when for judging that the first voltage signal is more than the first threshold voltage of setting, stops output PWM
Pulse；Or fracture stops exporting pwm pulse to power device when having interrupt signal in judging.
Preferably, first current sampling module includes：First current sampling resistor, first voltage converting unit；
First current sampling resistor is connected between the output negative pole of rectifier bridge and DC power cathode；
The first voltage converting unit, the current signal for sampling first current sampling resistor are converted to electricity
After pressing signal, it is sent to the A/D mouths of the MCU.
Preferably, the first voltage converting unit includes：
First operational amplifier, second operational amplifier, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance,
Seven resistance and the 8th resistance；
The normal phase input end of first operational amplifier is by the 8th resistance eutral grounding, and first operational amplifier is just
Phase input terminal connects 0~24V power supplys by the 7th resistance；
The inverting input of first operational amplifier connects the output end of first operational amplifier；
The output end of first operational amplifier connects the normal phase input end of second operational amplifier by the 5th resistance,
The normal phase input end of the second operational amplifier passes through the 6th resistance eutral grounding；
The output end of the second operational amplifier connects rectifier bridge by the 4th resistance being sequentially connected in series with 3rd resistor
Output negative pole；
The common end of inverting input the connection 3rd resistor and the 4th resistance of the second operational amplifier.
Preferably, the first voltage converting unit further includes：Third capacitance, the 4th capacitance, the 5th capacitance, the 6th electricity
Hold, the 7th capacitance；
The power supply of first operational amplifier passes through the third capacity earth；
The power supply of first operational amplifier passes through the 5th capacity earth；
The third capacitance is electrolytic capacitor, and the 5th capacitance is polarity free capacitor；
The inverting input of the second operational amplifier passes through the 4th capacity earth；
The normal phase input end of first operational amplifier passes through the 6th capacity earth；
0~24V power supplys pass through the 7th capacity earth.
Preferably, second current sampling module includes：Second current sampling resistor, second voltage comparing unit；
Second current sampling resistor is in series with the power device in active PFC circuit, is used for detection stream overpower
The current signal of device；
The second voltage comparing unit is used for the voltage directly proportional to the voltage on second current sampling resistor
It is compared with predeterminated voltage, when the voltage directly proportional to the voltage on second current sampling resistor is more than predeterminated voltage
When, send middle fracture of the interrupt signal to the MCU.
Preferably, the second voltage comparing unit includes：Eleventh resistor, thirteenth resistor, the 14th resistance and
Two comparators；
The normal phase input end of second comparator connects the direct current with second resistance by the eleventh resistor
Source cathode；
The inverting input of second comparator passes through described by the 14th resistance eutral grounding, the 14th resistance
13 resistance connect 0~24V power supplys；The 14th ohmically voltage is as the predeterminated voltage；
The middle fracture of the output end connection MCU of second comparator.
Preferably, the second voltage comparing unit further includes：13rd capacitance, the 14th capacitance, the 15th capacitance,
Nine resistance, the tenth resistance and the first diode；
The both ends of 13rd capacitance are separately connected the inverting input and ground of second comparator；
14th capacitance is connected in parallel on the both ends of the 14th resistance；
The both ends of 15th capacitance are separately connected the power supply and ground of the second comparator；
The inverting input of second comparator passes through the tenth resistance, the first diode, the 9th resistance that are sequentially connected in series
Connect 0~24V power supplys；
The power supply of second comparator is 0~24V.
Preferably, the MCU is additionally operable to judge when the first voltage signal is more than the second threshold voltage of setting, cuts
The current supply circuit to break to compressor；When the first voltage signal is more than the third threshold voltage of setting, for closing outdoor
Power supply.
Preferably, the active PFC circuit includes：Radio-frequency rector, power device, fast recovery diode, electrolytic capacitor；
The output cathode of the rectifier bridge passes sequentially through concatenated radio-frequency rector and connects direct current with fast recovery diode
Source anode；
The both ends of the electrolytic capacitor are separately connected the DC power anode and DC power cathode；
The common end of the radio-frequency rector and fast recovery diode is sampled by the power device being sequentially connected in series and second
Resistance connects DC power cathode.
Preferably, the active PFC circuit further includes filter capacitor；
The both ends of the filter capacitor are separately connected the output cathode and output negative pole of the rectifier bridge.
Compared with prior art, the present invention has the following advantages：
Active PFC overcurrent protection circuits provided in this embodiment had not only detected the electric current flowed through on power device, but also detection
The electric current of DC loop.In this way, since the overcurrent on power device is instantaneous value, flowed through on power device by detecting in real time
Electric current, when detecting that overcurrent occurs in the electric current on power device, in time stop output driving power device on off state
Pwm pulse.Also, the current feedback detected on power device to MCU is middle fracture, due to middle fracture response speed very
Soon, therefore, power device can be protected in time, in case power device is damaged because of overcurrent.Meanwhile passing through inspection
The corresponding first voltage signal of total current on commutating circuit is surveyed, first voltage signal is fed back to the A/D mouths of MCU, works as appearance
When overcurrent, stopping output can be according to first voltage signal when there is not overcurrent to the pwm pulse of power device grid
Size come closed loop feedback adjustment pwm pulse pulse width（Or duty ratio）To make the effect of power factor compensation be carried
It rises.
Description of the drawings
Fig. 1 is active one schematic diagram of PFC current foldback circuits embodiment provided by the invention；
Fig. 2 is the first current sampling module schematic diagram provided by the invention；
Fig. 3 is the second current sampling module schematic diagram provided by the invention；
Fig. 4 is the overcurrent protection circuit figure of active PFC provided by the invention.
Specific implementation mode
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, below in conjunction with the accompanying drawings to the present invention
Specific implementation mode be described in detail.
Referring to Fig. 1, which is active one schematic diagram of PFC current foldback circuits embodiment provided by the invention.
First, in order to make the technical solution those skilled in the art can better understand that with the implementation embodiment of the present invention,
The operation principle of active PFC circuit is introduced first below.
Active PFC circuit can be applied in the frequency control of air-conditioning, refrigerator, washing machine, fan electromotor etc., and the present invention carries
The scheme of confession does not limit to its specific application scenarios.
Active PFC circuit provided in this embodiment includes：Radio-frequency rector L, power device Q, fast recovery diode D, electricity
Solve capacitance C2；
The output cathode of the rectifier bridge DB passes sequentially through concatenated radio-frequency rector L and is connected directly with fast recovery diode C2
Flow positive pole DC+；
The both ends of the electrolytic capacitor C2 are separately connected the DC power anode DC+ and DC power cathode DC-；
It is adopted by the power device Q being sequentially connected in series and second common end of the radio-frequency rector L and fast recovery diode D
Sample resistance R2 connection DC power cathodes DC-.
The operation principle of active PFC circuit is：
After power device Q is connected, DC voltage is added in the both sides radio-frequency rector L, and L generates instantaneous large-current；The electric current
Power device Q is flowed into from the output cathode of rectifier bridge DB, then flow back into DC power cathode DC-.
When power device Q ends, the positive voltage of inducting generated on radio-frequency rector L makes electric current pass through fast recovery diode
D flows to electrolytic capacitor C2 and charges to it；Because the voltage of the one-way conduction characteristic of fast recovery diode D, C2 will not add
On the collector of power device Q, the grid of power device Q is connected with its power device driving circuit 2；Power device drives back
Road 2 is used to export the conducting and disconnection of pwm pulse driving Q；Q is set frequently to be connected and close when using the pwm pulse of high carrier frequency
When disconnected, DC current can be pulled up and constantly be charged to C2 by L, D, to play power factor compensation and promote DC voltage
Effect.
It should be noted that DC voltage refers to the voltage between DC+ and DC-.
The overcurrent protection circuit of active PFC provided in this embodiment, including：First current sampling module 3, the second electric current
Sampling module 4 and MCU5；
First current sampling module 3, for acquiring the first current signal in DC power supply circuit, by described first
Current signal carries out being converted to the A/D mouths that corresponding first voltage signal is sent to the MCU5；
Second current sampling module 4, for acquiring the second electric current flowed through on power device in active PFC circuit letter
Number, when second current signal is more than the second threshold current of setting, send middle fracture of the interrupt signal to the MCU5；
The MCU5 when for judging that the first voltage signal is more than the first threshold voltage of setting, stops output PWM
Pulse；Or fracture stops exporting pwm pulse to power device when having interrupt signal in judging.
Active PFC overcurrent protection circuits provided in this embodiment had not only detected the electric current flowed through on power device Q, but also inspection
Survey the electric current of DC loop.In this way, since the overcurrent on Q is instantaneous value, by detecting the electric current flowed through on Q in real time, work as inspection
When measuring the electric current on Q and overcurrent occur, stop the pwm pulse of output driving Q-switch state in time.Also, detect the electricity on Q
What stream fed back to MCU is middle fracture, due to middle fracture response speed quickly, Q can be protected in time, with
Exempt from Q to damage because of overcurrent.Meanwhile by detecting the corresponding first voltage signal of total current on commutating circuit, by first
Voltage signal feeds back to the A/D mouths of MCU, when there is overcurrent, stops pwm pulse of the output to Q grids, when there is not overcurrent
When, the pulse width of pwm pulse can be adjusted come closed loop feedback according to the size of first voltage signal（Or duty ratio）To make
The effect of power factor compensation gets a promotion.
It should be noted that if only detecting the electric current flowed through on Q, although can overcurrent be carried out to power device in real time
Protection.But due to not detecting the total current of commutating circuit, the superfluous overcurrent brought can not be compensated active PFC and carried out
Protection, and according to the instantaneous value of total current processing can not be compensated to carry out the pwm pulse width of closed loop feedback.
It should be noted that if only having detected the total current of commutating circuit, the current strap only detected on Q can be made up and come
The shortcomings that, but power device can not be protected in real time.This is because the overcurrent for flowing through power device is instantaneous value, although also can
Reflect on the sampling resistor of the total current of commutating circuit, but the feedback of the way circuit of commutating circuit is the A/D mouths of MCU, is not
Middle fracture.Since the response processing speed of software is slower, overcurrent protection can be caused not in time, may not be in time for also into
Row protection, power device have been damaged.
Therefore, overcurrent protection circuit provided in an embodiment of the present invention, respectively detect Q on electric current and commutating circuit it is total
Circuit can detect the instantaneous current value on Q, and be protected by the middle fracture of MCU in time in this way, carry out in this way
The fast response time of protection is risk of damage to so as to reduce Q.
It should be noted that the first current sampling resistor R1 in Fig. 1 belongs to the first current sampling module 3；Second electric current
Sampling resistor R2 belongs to the second current sampling module 4.
The first current sampling resistor R1 is connected between the output negative pole of rectifier bridge DB and DC power cathode DC-；
The second current sampling resistor R2 is in series with the power device Q in active PFC circuit.
It should be noted that the active PFC circuit further includes filter capacitor C1；
The both ends of the filter capacitor C1 are separately connected the output cathode and output negative pole of the rectifier bridge DB.
The effect of filter capacitor C1 be protect rectifier bridge DB not to be struck by lightning, the impact failures such as power-supply fluctuation；It has concurrently simultaneously
EMC noises are filtered out, the interference to power transmission electric network is reduced.
Referring to Fig. 2, which is the first current sampling module schematic diagram provided by the invention.
First current sampling module 3 provided in this embodiment includes：First current sampling resistor R1, first voltage conversion are single
Member 31；
The first current sampling resistor R1 is connected between the output negative pole of rectifier bridge and DC power cathode；
The first voltage converting unit 31, the current signal for sampling the first current sampling resistor R1 are converted
After voltage signal, it is sent to the A/D mouths of the MCU5.
Referring to Fig. 3, which is the second current sampling module schematic diagram provided by the invention.
Second current sampling module provided in this embodiment includes：Second current sampling resistor R2, second voltage are more single
Member 41；
The second current sampling resistor R2 is in series with the power device in active PFC circuit, flows through work(for detecting
The current signal of rate device Q；
The second voltage comparing unit 41, being used for will be directly proportional to the voltage on the second current sampling resistor R2
Voltage is compared with predeterminated voltage, when the voltage directly proportional to the voltage on the second current sampling resistor R2 is more than default
When voltage, middle fracture of the interrupt signal to the MCU5 is sent.
Below in conjunction with the accompanying drawings come be discussed in detail active PFC provided in an embodiment of the present invention overcurrent protection circuit one kind
Specific implementation.
It should be noted that power supply in the present invention can be the power supply of 0~24V, when concrete condition can preferred+5V,
It some application scenarios can preferred+15V.The voltage for the specific occasion having below can be not limited to specifically enumerate with different from
Voltage value.
Referring to Fig. 4, which is the overcurrent protection circuit figure of active PFC provided by the invention.
The first voltage converting unit 31 includes：
First operational amplifier IC1, second operational amplifier IC2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5,
6th resistance R6, the 7th resistance R7 and the 8th resistance R8；
The normal phase input end of the first operational amplifier IC1 passes through the 8th resistance R8 ground connection, first operation amplifier
The normal phase input end of device IC1 passes through the 7th resistance R7 connection+5V power supplys；
The inverting input of the first operational amplifier IC1 connects the output end of the first operational amplifier IC1；
The output end of the first operational amplifier IC1 by the 5th resistance R5 connection second operational amplifiers IC2 just
The normal phase input end of phase input terminal, the second operational amplifier IC2 passes through the 6th resistance R6 ground connection；
The output end of the second operational amplifier IC2 is connected by the 4th resistance R4 being sequentially connected in series with 3rd resistor R3
The output negative pole of rectifier bridge DB；
The common end of inverting input connection the 3rd resistor R3 and the 4th resistance R4 of the second operational amplifier IC2.
It should be noted that IC1 is voltage follower herein, IC2 is amplifier, and the advantages of design is can to improve in this way
The stability of hardware-in-the-loop.
It should be noted that the first current sampling signal of acquisition is converted to 0~5V's by first voltage converting unit 31
The A/D mouths of MCU are sent to after voltage signal.
It should be noted that the reference voltage of the normal phase input end of IC1 is the voltage on R8, R7 and R8 series connection are to 5V voltages
It is divided.
Required voltage V1 is obtained by R7, R8, IC1 design voltage follower（The 1 foot voltage of IC1）, then pass through R5, R6 points
Pressure design obtains the target reference voltage V2 of IC2（The 5 foot voltages of IC2）, will be electric finally by the formula scales of R3, R4, R1, V2
Stream sampled signal conversion zooms into the A/D voltage signals of the 7th feet of IC2 output.
The second voltage comparing unit 41 includes：Eleventh resistor R11, thirteenth resistor R13, the 14th resistance R14
With the second comparator IC3；
The normal phase input end of the second comparator IC3 connects institute by the eleventh resistor R11 with second resistance R2
State DC power cathode DC-；
The inverting input of the second comparator IC3 passes through the 14th resistance R14 ground connection, the 14th resistance R14
Pass through the thirteenth resistor R13 connections 5V power supplys；Voltage on the 14th resistance R14 is as the predeterminated voltage；
The middle fracture of the output end connection MCU5 of the second comparator IC3.
It should be noted that R13 and R14 series connection divides 5V as divider resistance, by the electricity on R14 after partial pressure
Press the reference voltage of the inverting input as IC3, i.e., the described predeterminated voltage.
The voltage that second sampled current signals generate is divided by R2 and R11, and the control source IC3 after partial pressure is just
Phase input terminal.
When the voltage of IC3 normal phase input ends is higher than the voltage on R14, the output signal of IC3, which will be sent, to be overturn, and is turned in this way
Rotaring signal is input to the middle fracture of MCU5.MCU5 carries out corresponding overcurrent protection.
It should be noted that in order to improve the anti-interference ability of the overcurrent protection circuit, filtering has also been devised in the present invention
Circuit.It continues with and describes in detail in conjunction with Fig. 4.
The second voltage comparing unit 41 further includes：13rd capacitance C13, the 14th capacitance C14, the 15th capacitance
C15, the 9th resistance R9, the tenth resistance R10 and the first diode D1；
The both ends of the 13rd capacitance C13 are separately connected the inverting input and ground of the second comparator IC3；
The 14th capacitance C14 is connected in parallel on the both ends of the 14th resistance R14；
The both ends of the 15th capacitance C15 are separately connected the power supply and ground of the second comparator IC3；
The inverting input of the second comparator IC3 by the tenth resistance R10 that is sequentially connected in series, the first diode D1,
9th resistance R9 connection+5V power supplys；
The power supply of the second comparator IC3 is+15V.
The effect of C13 is to filter out the noise of the second sampled current signals；
The effect of C14 is the noise in the reference voltage of the inverting input in order to filter out IC3；
The effect of C15 is the smooth and filtering between the power supply+15V in order to make IC3 and ground G.
The first voltage converting unit further includes：Third capacitance C3, the 4th capacitance C4, the 5th capacitance C5, the 6th capacitance
C6, the 7th capacitance C7；
The power supply of the first operational amplifier IC1 is grounded by the third capacitance C3；
The power supply of the first operational amplifier IC1 is grounded by the 5th capacitance C5；
C3 is electrolytic capacitor；It mainly plays smoothing effect, have filter action concurrently；
C5 is polarity free capacitor, is played a filtering role；
By C3 and C5, the two hold ground connection to 15V, and supply voltage stability improves, and noise jamming is reduced.
The inverting input of the second operational amplifier IC2 is grounded by the 4th capacitance C4；
The normal phase input end of the first operational amplifier IC1 is grounded by the 6th capacitance C6；
+ 5V the power supplys are grounded by the 7th capacitance C7.
The effect of C4 is to filter out IC2 inverting inputs（6th foot）Input signal in noise；
The effect of C6 is to filter out IC1 normal phase input ends（3rd foot）Input signal in noise；
C7 is electrolytic capacitor；The main smoothing effect for playing 5V power supplys has filter function concurrently.
D1 and R10 Combination Designs are to improve the stability of comparator.
It should be noted that in the overcurrent protection circuit that above example of the present invention provides, the MCU is additionally operable to judge
When the first voltage signal is more than the second threshold voltage of setting, cut off to the current supply circuit of compressor；When described first
When voltage signal is more than the third threshold voltage of setting, for closing all power supplies.
It is understood that since the feedback end for detecting DC loop total current in the embodiment of the present invention is the A/D of MCU
Mouthful, therefore, MCU is by judging that the size of the voltage signal of A/D implements the control strategy of different stage.
For example, three protection levels of setting.Corresponding first threshold voltage is 3.8V, and the second threshold voltage is
4.2V, third threshold voltage are 4.5V etc..It should be noted that these three threshold voltages can freely be set according to actual needs
Different numerical value, is merely illustrative of herein, does not limit to specific numerical value.
When first voltage signal is less than 3.8V, MCU only controls the pulse width of PWM, does not stop exporting pwm pulse.This
Sample can improve the power factor of entire air-conditioning system.
When first voltage signal, which is more than or equal to 3.8V, is less than 4.2V, MCU stops output pwm pulse；
When first voltage signal, which is more than or equal to 4.2V, is less than 4.5V, MCU stops output pwm pulse, and controls compression
Machine is out of service；It can ensure the safety of entire air-conditioning system in this way.
When first voltage signal is more than or equal to 4.5V, MCU, which controls the power supply outside air conditioning chamber, to be stopped.
It should be noted that the various guarantors implemented for the detection of commutating circuit total current in above example of the present invention
Shield can also detect the total current in AC power supplies circuit by adding Current Transmit in AC power supplies circuit, and then realize each
Kind protection, principle is identical as the detection principle of total current of commutating circuit, and details are not described herein.
The above described is only a preferred embodiment of the present invention, being not intended to limit the present invention in any form.Though
So the present invention has been disclosed as a preferred embodiment, and however, it is not intended to limit the invention.It is any to be familiar with those skilled in the art
Member, without departing from the scope of the technical proposal of the invention, all using the methods and technical content of the disclosure above to the present invention
Technical solution makes many possible changes and modifications, or is revised as the equivalent embodiment of equivalent variations.Therefore, it is every without departing from
The content of technical solution of the present invention, according to the technical essence of the invention any simple modification made to the above embodiment, equivalent
Variation and modification, still fall within technical solution of the present invention protection in the range of.
Claims (10)
1. a kind of overcurrent protection circuit of active PFC, which is characterized in that including：First current sampling module, the second electric current are adopted
Egf block and MCU；
First current sampling module, for acquiring the first current signal in DC power supply circuit, by first electric current
Signal carries out being converted to the A/D mouths that corresponding first voltage signal is sent to the MCU；
Second current sampling module, for acquiring the second current signal flowed through on power device in active PFC circuit, when
When second current signal is more than the second threshold current of setting, middle fracture of the interrupt signal to the MCU is sent；
The MCU when for judging that the first voltage signal is more than the first threshold voltage of setting, stops output pwm pulse；
Or fracture stops exporting pwm pulse to power device when having interrupt signal in judging.
2. the overcurrent protection circuit of active PFC according to claim 1, which is characterized in that first current sample
Module includes：First current sampling resistor, first voltage converting unit；
First current sampling resistor is connected between the output negative pole of rectifier bridge and DC power cathode；
The first voltage converting unit, the current signal for sampling first current sampling resistor are converted to voltage letter
After number, it is sent to the A/D mouths of the MCU.
3. the overcurrent protection circuit of active PFC according to claim 2, which is characterized in that the first voltage conversion
Unit includes：
First operational amplifier, second operational amplifier, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 7th electricity
Resistance and the 8th resistance；
For the normal phase input end of first operational amplifier by the 8th resistance eutral grounding, the positive of first operational amplifier is defeated
Enter end and 0~24V power supplys are connected by the 7th resistance；
The inverting input of first operational amplifier connects the output end of first operational amplifier；
The output end of first operational amplifier connects the normal phase input end of second operational amplifier by the 5th resistance, described
The normal phase input end of second operational amplifier passes through the 6th resistance eutral grounding；
The output end of the second operational amplifier connects the defeated of rectifier bridge with 3rd resistor by the 4th resistance being sequentially connected in series
Go out cathode；
The common end of inverting input the connection 3rd resistor and the 4th resistance of the second operational amplifier.
4. the overcurrent protection circuit of active PFC according to claim 3, which is characterized in that the first voltage conversion
Unit further includes：Third capacitance, the 4th capacitance, the 5th capacitance, the 6th capacitance, the 7th capacitance；
The power supply of first operational amplifier passes through the third capacity earth；
The power supply of first operational amplifier passes through the 5th capacity earth；
The third capacitance is electrolytic capacitor, and the 5th capacitance is polarity free capacitor；
The inverting input of the second operational amplifier passes through the 4th capacity earth；
The normal phase input end of first operational amplifier passes through the 6th capacity earth；
0~24V power supplys pass through the 7th capacity earth.
5. the overcurrent protection circuit of active PFC according to claim 1, which is characterized in that second current sample
Module includes：Second current sampling resistor, second voltage comparing unit；
Second current sampling resistor is in series with the power device in active PFC circuit, is used for detection stream overpower device
Current signal；
The second voltage comparing unit, for by the voltage directly proportional to the voltage on second current sampling resistor and in advance
If voltage is compared, when the voltage directly proportional to the voltage on second current sampling resistor is more than predeterminated voltage, hair
Send interrupt signal to the middle fracture of the MCU.
6. the overcurrent protection circuit of active PFC according to claim 5, which is characterized in that the second voltage compares
Unit includes：Eleventh resistor, thirteenth resistor, the 14th resistance and the second comparator；
It is negative that the normal phase input end of second comparator connects the DC power supply by the eleventh resistor with second resistance
Pole；
The inverting input of second comparator passes through the described 13rd by the 14th resistance eutral grounding, the 14th resistance
Resistance connects 0~24V power supplys；The 14th ohmically voltage is as the predeterminated voltage；
The middle fracture of the output end connection MCU of second comparator.
7. the overcurrent protection circuit of active PFC according to claim 6, which is characterized in that the second voltage compares
Unit further includes：13rd capacitance, the 14th capacitance, the 15th capacitance, the 9th resistance, the tenth resistance and the first diode；
The both ends of 13rd capacitance are separately connected the inverting input and ground of second comparator；
14th capacitance is connected in parallel on the both ends of the 14th resistance；
The both ends of 15th capacitance are separately connected the power supply and ground of the second comparator；
The inverting input of second comparator connects 0 by the tenth resistance, the first diode, the 9th resistance being sequentially connected in series
~24V power supplys；
The power supply of second comparator is 0~24V.
8. active PFC overcurrent protection circuits according to claim 1, which is characterized in that the MCU is additionally operable to judge to work as
When the first voltage signal is more than the second threshold voltage of setting, cut off to the current supply circuit of compressor；When first electricity
When signal being pressed to be more than the third threshold voltage of setting, for closing outdoor power supply.
9. according to the overcurrent protection circuit of the active PFC of claim 2-4 any one of them, which is characterized in that described active
Pfc circuit includes：Radio-frequency rector, power device, fast recovery diode, electrolytic capacitor；
The output cathode of the rectifier bridge passes sequentially through concatenated radio-frequency rector and is connecting DC power supply with fast recovery diode just
Pole；
The both ends of the electrolytic capacitor are separately connected the DC power anode and DC power cathode；
The common end of the radio-frequency rector and fast recovery diode passes through the power device and the second sampling resistor that are sequentially connected in series
Connect DC power cathode.
10. the overcurrent protection circuit of active PFC according to claim 9, which is characterized in that the active PFC circuit
It further include filter capacitor；
The both ends of the filter capacitor are separately connected the output cathode and output negative pole of the rectifier bridge.
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| BE1022018B1 (en) * | 2013-08-14 | 2016-02-04 | Cockerill Maintenance & Ingenierie S.A. | DEVICE FOR SWITCHING AND REMOTELY PROTECTING ELECTRICAL SYSTEMS. |
| CN105006805B (en) * | 2015-08-28 | 2017-08-25 | 广东美的制冷设备有限公司 | The overcurrent protective device and method of PFC pfc circuit |
| CN113746066B (en) * | 2020-05-29 | 2022-12-09 | 比亚迪股份有限公司 | Current converter overcurrent protection method and circuit and current converter controller |
| CN112290506B (en) * | 2020-09-29 | 2022-06-07 | 四川虹美智能科技有限公司 | Surge protection device and method |
| CN114006524B (en) * | 2021-11-05 | 2023-06-27 | 上海儒竞智控技术有限公司 | Method, medium, control circuit and Boost PFC control system for inhibiting overcurrent |
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| CN201774245U (en) * | 2010-07-30 | 2011-03-23 | 宁波奥克斯空调有限公司 | PFC overcurrent protecting circuit |
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